Bleaching textile fibers



lAug. 26, 1930. H. P. BENSON BLEACHING TEXTILE FIBERS Filed Nov. 7, 1928 Inlawoa: Hemi env/6021,. @6% f Patented Aug. 2.6, 1930 PATENT 'ol-Fica HENRY r. BENSON, or SALEM, mssacrrusamrs :BLEACHING TEXTILE EIBEBs Application 1ed-N'ovember 7, 1928. Serial No. 317,834'.

My invention relates to methods of and apparatus for bleaching textile fabrics, .such as 'cotton yarn and cloth, by use of actinic ra s.

yThe invention will be best understood from the following description of an example of the practice of the improved method and of an example ofapparatus for use in such practice, especially when read in the light 'of the accompanying drawings, while thefscope of the invention will be more particularly pointed out in the appended-claims.

The drawings schematically illustrate an example of apparatus embodying the invention.

' Hitherto it has been common practice to bleach cotton fabrics woven in natural color by an expensive time-consuming process involving successive treatments of the fabric with alkalis and acids with intermediate washing in water. This method can be practised commercially only where pure water in large quantity is available, as the practice necessitates the use of about 1,000,000 gallons for each 25,000 pounds of fabric treated, and as a commercial plant commonly treats from 20,000 to 100,000 pounds of fabric daily it will be readily appreciated that the amount of water consumed and the expense incident thereto in many instances and locations is so great as -to be commercially prohibitive. Further, the acids and alkalis (commonly sulphuric or hydrochloric acid and soda-ash) with which the fabric is treated results in a weakened texture which for man uses of the fabric prohibits it being bleache Commonly the present method takes about four days to bleach the usual. grades of cotton cloth.

According to the improved method, which involves the bleaching of the fabric or yarn with so-called actinic rays, as, for example, ultra-violet light, with elimination of all or most of the treatment with strong acids and alkalis, the amount of water necessary as compared with prior methods may be reduced about 50% and the time for carrying out the method reduced from about 25%fto 50%, while. a resultant stronger bleached fabric may be produced. Consequently the improved method not only results in an improved bleached product but effects a great and desirable economic saving in water and time with decreased maintenance Vand installation costs. The saving in water, it will be appreciated, permits the improved method to be practised in localities where it is impossible to practise the prior method.

As an example of the -improved method, but without limitation thereto, assuming that cot,- ton cloth woven in the natural color in the grey as it is termed, is to be bleached and said cloth has the warp thereof impregnated with starch, as commonly would be the case, it may be first subjected to a stripping process, that is,l treated to remove' the starch. For carrying out this step of the method the cloth maybe vrun from a roll through a vat containing a warm,weak solution of diastofor at such speed as will cause'the cloth leaving the vat to-be saturated. The cloth leaving the vat may be run through squeeze rolls to remove the excess solution and then may be plated down and allowed to'stand for about two hours, after which the cloth may be washed in a washing machine to remove the treated starch, and then the cloth may be dried. The cloth may then betreated with milk of lime; for example, it may be run from a roll through 'a vat containing a 10% Twaddell milk of lime solution at such speed as will saturate the cloth. c The cloth leaving the vat may be passed through squeeze rolls to remove the excess solution. I have found that thel treatment of the cloth with the milk of lime solution breaks down the natural waxes and oils of the fiber andimproves the effect of the subsequent treatment of the fabric by actinic rays.`

After being treated withv milk of lime as above described, and while the fabric is still moist, it may be subjected to the action of the actinc rays, preferably ultra-violet lightLfor about six hours. I have found that to prevent injury to the cloth during its treatment with ultra-violet rays best results are secured by keeping the cloth wet. After a treatment of the cloth by use of ultra-violet rays itfma then be washed in water to'remove the''mll- Y of lime and dried.

As an example of apparatusg-for-car'rying out the improvedv method the stripof cloth 1 may be fed from a roll 3 over guide pulleys 5 through avat 7 containing the milk of lime above referred. to. Leaving the vat the cloth may pass between the squeeze rolls 9 to refmove the excess liquid and then may pass to a so-called tenterlng machine compris- 'position and passed about the guide pulleys 17 through a vat 19 containing water for washing the cloth, after which the cloth may be passed through a drier 21 from which it is delivered toa roll 23.

At the tentering machine, and preferably at opposite sides of the vertical sheet of cloth passing therethrough, are arranged lamps 25 which generate ultra-violet light, said light materially concentrated as compared w1 natural ultra-violet light, while at convenient intervals throughout the length of the mawoven with a starched warp which comprises chine may be arranged spray pipes 27 for sprayin the cloth with water to keep it moist. I have ound that satisfactory results can be obtained when the speed of the cloth passing through thetentering machine with respect to the number of lamps is such as to subject the clo'th to the ultra-violet rays for about six hours, under which conditions the concentration of the ultra-violet light may be that produced by 900 watt ultra-violet lamps spaced about 18 inches from the cloth.

When necessary and desirable, lf the cloth contains motes or other foreign matter, it may be treated for removal of the same by an,acid and boiling process lafter it leaves the vat 19. 4

I have found-that other alkalisv such as lime water, and water solutions of soda-ash` and caustic soda, may be substituted for milk of lime in the above rocess, but that the bleaching is less rapidi;1 effected with these substitutes. I have also found that where .treatment with alkali is omitted, the bleaching may be eiected if the fabric material is kept moistened with water while subjected to the ultra-violet light; but that the bleach- A ing action in this case is much slower.

Although I`have described for pur oses of illustration a particular example of t e practice of the improved method and an example of apparatus for.` use therewith, it will be understood vthat 'within the scope ofthe' invention wide deviations may be made therefrom without departing from its spirit, and that my Ainvention is not limited to use for bleaching yarn as well -as cloth and other textile fabrics clth or cotton textiles, but thatas well as cotton fabrics may be similarly treated. l

Claims:

1. The method of bleaching textile fibers 2. The method of bleaching textile libers i which comprises exposing them to the action Aof artificial ultra-violet light while moistened with milk of lime.

3. The method of bleaching cotton fabrics woven with a starched warp which comprises treating the cloth to remove the starch and afterwards sub'ecting the fabric to the action of ultra-violet light while moistened with an alkaline substance.

4., The method `of bleaching cotton fibers which comprises removing therefrom the waxes and fats, and afterwards exposing said fibers to ultra-violet light while moistened with milk of lime.

5. The method of bleaching cotton fibers which com rises removing therefrom the waxes and ats, and afterwards exposing said th fibers to ultra-violet light while moistened with an alkaline substance.

6. The method of bleaching cotton fabrics treating the cloth to remove the starch and afterwards subjecti g. the fabric to the action of ultra-violet.. lig t while moistened with milk of lime.

7. The method of bleaching cotton fabrics woven with a starched warp which comprises treating them with a diastofor solution for digesting the starch, washing the fabric to remove the digested starch, treating the fabric A with milk of lime for removing waxes and fats, and exposing the fabric to ultra-violet light while moistened with the milk of lime.

8. The method of bleaching cotton fabrics woven with a starched warp which comprises treating them with a diastofor solution for digestin the starch, washing the fabric to remove't 'e digested starch, treating the fabric with alkali for removing waxes and fats, and exposing the fabric to ultra-violet light while moistened with an alkaline substance. In testimony whereof,. I have signed my name to this specification.A

HENRY P. BENSON. 

